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Lithocholic acid was identified as a molecular glass host material for room temperature phosphorescent (RTP) chromophores. Differential scanning calorimetry (DSC) was performed on a series of structurally similar, biologically sourced molecules, including lithocholic acid, β‐estradiol, cholesterol, and β‐sitosterol, in an effort to identify new amorphous molecular glasses independent of plasticizing additives. DSC analysis revealed lithocholic acid and β‐estradiol form stable molecular glasses post thermal processing unlike neat cholesterol and β‐sitosterol. The ability of lithocholic acid and β‐estradiol to stabilize high wt. % loadings of d10‐pyrene and a mixture of d10‐pyrene and an iridium chromophore, bis(2,4‐difluorophenylpyridinato)‐tetrakis(1‐pyrazolyl)borate iridium(III) (FIr6), was also investigated. All β‐estradiol formulations show β‐estradiol cold crystallization. Optical microscopy and wide angle X‐ray scattering measurements suggest spherulite β‐estradiol crystals form during this process. Finally, time‐resolved luminescence and phosphorescence quantum yield experiments show that the d10‐pyrene RTP lifetime is longer and the d10‐pyrene phosphorescence quantum yield is higher in lithocholic acid molecular glasses than in β‐estradiol molecular glasses. The discrepancy in lifetime and quantum yield values is explained by quantitatively smaller rates of non‐radiative decay from the triplet state of d10‐pyrene in lithocholic acid. [ABSTRACT FROM AUTHOR]

The fabrication, molecular structure, and spectroscopy of a stable cholesteric liquid crystal platinum acetylide glass obtained from trans‐Pt(PEt3)2(CC−C6H5−CN)(CC−C6H5−COO−Cholesterol), are described and designated as PE1‐CN‐Chol. Polarized optical microscopy, differential scanning calorimetry, and wide‐angle X‐ray scattering experiments show room temperature glassy/crystalline texture with crystal formation upon heating to 165 °C. Further heating results in conversion to cholesteric phase. Cooling to room temperature leads to the formation of a cholesteric liquid crystal glass. Scanning tunneling microscopy of a PE1‐CN‐Chol monolayer reveals self‐assembly at the solid−liquid interface with an array of two molecules arranged in pairs, oriented head‐to‐head through the CN groups, giving rise to a lamella arrangement. The lamella structure obtained from molecular dynamics calculations shows a clear phase separation between the conjugated platinum acetylide and the hydrophobic cholesterol moiety with the lamellae separation distance being 4.0 nm. Ultrafast transient absorption and flash photolysis spectra of the glass show intersystem crossing to the triplet state occurring within 100 ps following excitation. The triplet decay time of the film compared to aerated and deoxygenated solutions is consistent with oxygen quenching at the film surface but not within the film. The high chromophore concentration, high glass thermal stability, and long triplet lifetime in air show that these materials have potential as nonlinear absorbing materials. [ABSTRACT FROM AUTHOR]